As summer winds down, here is a brief overview of the sunshine vitamin. The very important hormone-like Vitamin D.
Vitamin D is a fat-soluble vitamin with a similar structure to bodily hormones. Unlike other vitamins, vitamin D can be produced by the body, requiring exposure to sunlight. Like hormones, vitamin D regulates genetic expression. Vitamin D acts on the intestines, bones, and kidneys to maintain stable levels of calcium in the blood, and improves absorption and utilization of calcium and phosphorous. This provides benefits for bone health, regulation of blood pressure, maintenance of a stable nervous system, and normal heart action.
Overt vitamin D deficiency manifests as rickets (softening of bone and seizures) in children, and osteomalacia (demineralization of bone) in adults. Low levels of vitamin D can contribute to many other chronic diseases including hypertension, respiratory and cardiovascular problems, musculoskeletal disorders, inflammatory disorders including psoriasis and cancer, and decreased immune regulation, leading to autoimmune diseases and/or decreased resistance to infection.
The biologically active form of the vitamin, as made by the body is Vitamin D3. Vitamin D2 exists in foods like mushrooms, fatty fish, egg yolk, liver, and fortified foods. The amount in foods is insufficient, especially for people with impaired digestion from conditions such as inflammatory bowel disease, celiac disease, cystic fibrosis, ulcerative colitis, or Crohn’s disease.
The best way to obtain vitamin D is through exposure to sunlight. The amount of vitamin D made depends on the time of year, time of day, the latitude, how much skin is exposed, and how dark the person’s skin is at the time of exposure. With sunscreen on, people’s ability to absorb vitamin D is decreased by about 90%. That said, it is still important to protect yourself from too much sun exposure to prevent risk of skin cancer and early aging.
Current daily recommendations of vitamin D are controversial, ranging from 200-600 IU, or more. Supplementation may be necessary if blood levels are low, especially in the winter months in northern latitudes where exposure to the sun is far too low for optimal vitamin D production. Check with your medical provider about testing your serum vitamin D levels, especially if you have any conditions that could be affected by low levels.
For more information and current research on vitamin D, visit www.vitamindcouncil.org/about-vitamin-d/